Compacting polymeric powders is a well known process. An example thereof is known from WO 2009/153,318 wherein a polymeric powder is compressed in an isobaric press at a temperature below the melting point of the powder. WO 2009/153,318 also mentions that a carrier material may be used to support the polymeric powder during compaction.
It was observed that the process of WO 2009/153,318 like other known processes for compacting polymeric powders has a reduced efficiency in achieving a homogeneous compaction of the polymeric powder. It was further observed that the compacted polymeric powders obtained with known processes show rather large density variations across their surface, a phenomenon known as ribbing. It is also known that the phenomenon of ribbing may affect in a deleterious way the mechanical properties of various products obtained by further processing the compacted polymeric powder.
An aim of the invention may be to provide a process for compacting polymeric powders, which shows the mentioned disadvantages to a lesser extent.
The present invention provides a process for compacting a polymeric powder in a press, wherein the polymeric powder is supported during compaction by a powder carrier, wherein said powder carrier comprises a layer of a thickness (T), said layer comprising a material with a static coefficient of friction (COF), and wherein T×COF is at least 10 μm.
It was observed that the process of the invention, also referred to as the inventive process, is efficient in achieving a good compaction of the polymeric powder.
In particular it was observed that a compacted polymeric powder obtained by the inventive process shows less ribbing than known compacted polymeric powders. The invention therefore relates also to a compacted polymeric powder obtained by the inventive process.